The mixing can be done with a fork, though an electric mixer may be faster for whipping the egg whites.
Tiramisu tends to expand to fill the container, so use a dish that fits the portion size well.
For the sugar measurement, if you lack a scale, an empty 150g Mascarpone container can be used as a rough guide for volume, as the densities are similar.
American cooks may need to ensure they are using room temperature eggs for better whipping results.